You can still play today by utilizing Flash preservation software like BlueMaxima's Flashpoint, which completely bypasses the defunct Disney XD servers.
While the original official URL is defunct, the game's life continues through community efforts, allowing fans to relive the adventures of Beck, the Renegade, in the digital world of Argon City.
The Tron Uprising community has developed several fixes:
Type TRON Uprising: Escape From Argon City or simply Escape From Argon City . 3. Apply the Built-In Flash Player Fix